Error - The 'ObjectContent`1' type failed to serialize the response

Question

Hi   I am getting below error -   This XML file does not appear to have any style information associated with it. The document tree is shown below.   An error has occurred. The 'ObjectContent`1' type failed to serialize the response body for content type 'application/xml; charset=utf-8'. System.InvalidOperationException An error has occurred. Type 'System.Data.Entity.DynamicProxies.Employee_E9CD46600E1BE7E98203EB96803DFD66938EC862164FCCE4C5002C91CF8C9A5A' with data contract name 'Employee_E9CD46600E1BE7E98203EB96803DFD66938EC862164FCCE4C5002C91CF8C9A5A:http://schemas.datacontract.org/2004/07/System.Data.Entity.DynamicProxies' is not expected. Consider using a DataContractResolver if you are using DataContractSerializer or add any types not known statically to the list of known types - for example, by using the KnownTypeAttribute attribute or by adding them to the list of known types passed to the serializer. System.Runtime.Serialization.SerializationException at System.Runtime.Serialization.XmlObjectSerializerWriteContext.SerializeAndVerifyType(DataContract dataContract, XmlWriterDelegator xmlWriter, Object obj, Boolean verifyKnownType, RuntimeTypeHandle declaredTypeHandle, Type declaredType) at System.Runtime.Serialization.XmlObjectSerializerWriteContext.SerializeWithXsiType(XmlWriterDelegator xmlWriter, Object obj, RuntimeTypeHandle objectTypeHandle, Type objectType, Int32 declaredTypeID, RuntimeTypeHandle declaredTypeHandle, Type declaredType) at System.Runtime.Serialization.XmlObjectSerializerWriteContext.InternalSerialize(XmlWriterDelegator xmlWriter, Object obj, Boolean isDeclaredType, Boolean writeXsiType, Int32 declaredTypeID, RuntimeTypeHandle declaredTypeHandle) at WriteArrayOfEmployeeToXml(XmlWriterDelegator , Object , XmlObjectSerializerWriteContext , CollectionDataContract ) at System.Runtime.Serialization.CollectionDataContract.WriteXmlValue(XmlWriterDelegator xmlWriter, Object obj, XmlObjectSerializerWriteContext context) at System.Runtime.Serialization.XmlObjectSerializerWriteContext.WriteDataContractValue(DataContract dataContract, XmlWriterDelegator xmlWriter, Object obj, RuntimeTypeHandle declaredTypeHandle) at System.Runtime.Serialization.XmlObjectSerializerWriteContext.SerializeWithoutXsiType(DataContract dataContract, XmlWriterDelegator xmlWriter, Object obj, RuntimeTypeHandle declaredTypeHandle) at System.Runtime.Serialization.DataContractSerializer.InternalWriteObjectContent(XmlWriterDelegator writer, Object graph, DataContractResolver dataContractResolver) at System.Runtime.Serialization.DataContractSerializer.InternalWriteObject(XmlWriterDelegator writer, Object graph, DataContractResolver dataContractResolver) at System.Runtime.Serialization.XmlObjectSerializer.WriteObjectHandleExceptions(XmlWriterDelegator writer, Object graph, DataContractResolver dataContractResolver) at System.Runtime.Serialization.DataContractSerializer.WriteObject(XmlWriter writer, Object graph) at System.Net.Http.Formatting.XmlMediaTypeFormatter.WriteToStream(Type type, Object value, Stream writeStream, HttpContent content) at System.Net.Http.Formatting.XmlMediaTypeFormatter.WriteToStreamAsync(Type type, Object value, Stream writeStream, HttpContent content, TransportContext transportContext, CancellationToken cancellationToken) --- End of stack trace from previous location where exception was thrown --- at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at System.Web.Http.WebHost.HttpControllerHandler. d__1b.MoveNext()   private PMDbEntities db = new PMDbEntities(); public IHttpActionResult GetEmployees() { var results = db.Employees.ToList(); return Ok(results); }   Thanks

Ramco Ramco · Answer

Hi Jignesh     public partial class Employee { public Employee() { CreatedOn = DateTime.Now; } public int ID { get; set; } public string Name { get; set; } public string Email { get; set; } public string Gender { get; set; } public Nullable Salary { get; set; } public Nullable DepartmentId { get; set; } public string Active { get; set; } [Display(Name = "Created On")] [DataType(DataType.Date)] [DisplayFormat(DataFormatString = "{0:dd/MM/yyyy}")] public Nullable CreatedOn { get; set; } public Nullable UpdatedOn { get; set; } public virtual Department Department { get; set; } }   public partial class Department { [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2214:DoNotCallOverridableMethodsInConstructors")] public Department() { this.Employees = new HashSet (); } public int ID { get; set; } public string Name { get; set; } public string Location { get; set; } [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2227:CollectionPropertiesShouldBeReadOnly")] public virtual ICollection Employees { get; set; } }   Below is the Table content.   GO /****** Object: Table [dbo].[Departments] Script Date: 16-02-2021 19:17:52 ******/ SET ANSI_NULLS ON GO SET QUOTED_IDENTIFIER ON GO SET ANSI_PADDING ON GO CREATE TABLE [dbo].[Departments]( [ID] [int] IDENTITY(1,1) NOT NULL, [Name] [varchar](50) NULL, [Location] [varchar](50) NULL, PRIMARY KEY CLUSTERED ( [ID] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] ) ON [PRIMARY] GO SET ANSI_PADDING OFF GO /****** Object: Table [dbo].[Employees] Script Date: 16-02-2021 19:17:52 ******/ SET ANSI_NULLS ON GO SET QUOTED_IDENTIFIER ON GO SET ANSI_PADDING ON GO CREATE TABLE [dbo].[Employees]( [ID] [int] IDENTITY(1,1) NOT NULL, [Name] [varchar](50) NULL, [Email] [varchar](50) NULL, [Gender] [varchar](50) NULL, [Salary] [int] NULL, [DepartmentId] [int] NULL, [Active] [varchar](1) NULL, [CreatedOn] [date] NULL, [UpdatedOn] [date] NULL, PRIMARY KEY CLUSTERED ( [ID] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] ) ON [PRIMARY] GO SET ANSI_PADDING OFF GO SET IDENTITY_INSERT [dbo].[Departments] ON INSERT [dbo].[Departments] ([ID], [Name], [Location]) VALUES (1, N'IT', N'Mumbai') INSERT [dbo].[Departments] ([ID], [Name], [Location]) VALUES (2, N'HR', N'Delhi') INSERT [dbo].[Departments] ([ID], [Name], [Location]) VALUES (3, N'Sales', N'Hyderabad') SET IDENTITY_INSERT [dbo].[Departments] OFF SET IDENTITY_INSERT [dbo].[Employees] ON INSERT [dbo].[Employees] ([ID], [Name], [Email], [Gender], [Salary], [DepartmentId], [Active], [CreatedOn], [UpdatedOn]) VALUES (1, N'Mark', N'Mark@g.com', N'Male', 60000, 1, NULL, NULL, NULL) INSERT [dbo].[Employees] ([ID], [Name], [Email], [Gender], [Salary], [DepartmentId], [Active], [CreatedOn], [UpdatedOn]) VALUES (2, N'Steve', N'Steve@g.com', N'Male', 45000, 3, NULL, NULL, NULL) INSERT [dbo].[Employees] ([ID], [Name], [Email], [Gender], [Salary], [DepartmentId], [Active], [CreatedOn], [UpdatedOn]) VALUES (3, N'Pam', N'Pam@g.com', N'Female', 60000, 1, NULL, NULL, NULL) INSERT [dbo].[Employees] ([ID], [Name], [Email], [Gender], [Salary], [DepartmentId], [Active], [CreatedOn], [UpdatedOn]) VALUES (4, N'Sara', N'Sara@g.com', N'Female', 345000, 3, NULL, NULL, NULL) INSERT [dbo].[Employees] ([ID], [Name], [Email], [Gender], [Salary], [DepartmentId], [Active], [CreatedOn], [UpdatedOn]) VALUES (5, N'Ben', N'Ben@g.com', N'Male', 70000, 1, NULL, NULL, NULL) INSERT [dbo].[Employees] ([ID], [Name], [Email], [Gender], [Salary], [DepartmentId], [Active], [CreatedOn], [UpdatedOn]) VALUES (6, N'Philip', N'Philip@g.com', N'Male', 45000, 2, NULL, NULL, NULL) INSERT [dbo].[Employees] ([ID], [Name], [Email], [Gender], [Salary], [DepartmentId], [Active], [CreatedOn], [UpdatedOn]) VALUES (7, N'Mary', N'Mary@g.com', N'Female', 30000, 2, NULL, NULL, NULL) INSERT [dbo].[Employees]…

Jignesh Kumar · Answer

Hi,   its problem with you class properties and Table which pointed to  db.Employees. Please correct properties in Employee Entity class.